Prosser Offices
Prosser is the County seat for Benton County. The Courthouse, built in 1926, is located at 620 Market Street, and contains offices for the Auditor, Treasurer, Public Works and Road Department, Central Services, Assessor, Clerk, District Court, Geographic Information Systems, Sheriff civil deputy, and the County Commissioners.

The Planning Department Annex is near the Courthouse at 1002 Dudley Avenue.

The WSU Copperative Extension is across the street from the Courthouse at 1121 Dudley Avenue.

The Public Works Maintenance Shop is located near Prosser at 14303 N Hinzerling Road.

Kennewick Offices
The Benton County Annex is located at 5600 W Canal Place in Kennewick, and contains offices for the Assessor, Auditor, Building Department, and Treasurer. The Juvenile Justice Center is also located next to the County Annex.

The Benton County Justice Center is located in Kennewick at 7122 W Okanogan Place and contains offices for Superior Court, District Court, Information Technology (IT), Clerk, Facilities, Parks, Sheriff, Office of Public Defense, Human Resources, Prosecuting Attorney, Sustainable Development, and the Civil Service Commission. The Benton County Jail is located next to the Justice Center. The Coroner's building is located across the parking lot from the Justice Center.

The south county Public Works Road Maintenance Shop is at 102808 Wiser Parkway.

The Benton County Fairgrounds are located at 1500 S Oak Street.

The Benton-Franklin Human Services (Suite 201) and Benton County WSU Extension (Suite 102) offices are located in the Benton Franklin Health District Building at 7102 W Okanogan Place.

Richland Offices
The Auditor's Richland Substation is located in the Fred Meyer Plaza, 101 Wellsian Way Suite E.